I have decided to start working on RC planes again. I chose the MQ-9 Reaper as my new build.

This bird is distributed by Nitro Planes. I have to say, I am not entirely happy with the fiberglass work. I rewrote this first note, to display less irritation. I will attempt to correct the issues first encountered with this model. Although the quality is rather poor, it can be made into a reasonable model with some effort. This build was started with the intent of making it as scale as possible.

Take note that this thread will proceed slowly, as time and money allows. Okay, on to fixing the errors in the fiberglass parts. I started with the fuselage and the extremely poor fit of the various parts.

The first note of interest, is the main gear limbs. If anyone tried to use these limbs as they arrive in the kit, they are in for a sad and rude awakening. Note they are not the same. The gear would be off a significant amount, causing the model to sit awkwardly. Being a tripod gear setup, this would cause great instability. The wheel shafts they supply the kit with are extreme I think for this model. A great deal of weight. But.. in this build they will not be used, as my entire gear setup will be custom machined.

The only part of this setup that will be used, is the central portion of the limbs (as the real bird uses). The ends are useless in their stock model configuration. I will be cutting up the limbs and building a scale retractable assembly. This means machining aluminum parts, such as the hinges and axle assembly, with steel wheel shafts, as the real bird uses. The limbs are a bit wide for scale, but a band saw takes care of that. The LE and TE of the struts will be rounded as the real ones are, then sealed with epoxy for insertion into the machined aluminum ends.

In the first image posted, you can see not only the main struts, but also the front hood. The wood former inside is not glued in properly. It contacts the hood in a couple small places, but most of the hood is floating on glue. This method of insertion means that the fiberglass hood did not conform to the former, thus does not follow the designed shape. The following picture shows just how badly. You can see the new former I made and glued into the hood end. The end was originally fiberglass. It was too wide (4mm) than the fuselage where it mates. The bridge of fiberglass was cut and shortened, then the new former fitted and glued in place. This section of the hood now fits properly. Now to solve the other issues with the hood before it will satisfactorily fit the fuselage.

Images

In these views, you can see that the engine intake was molded from a mold that was not measured to insure the part would fit the fuselage. The aft end of the intake was 2mm too small on both sides. The rear exhaust port was too far away from its seat by 2mm.

This problem was solved by reducing the width of the fuselage on both sides. This was done by cutting a triangular slot in the fuselage and clamping both sides together. Epoxy was used to bond it together. The length gap was filled with a piece of ply. This served not only to fill the space, but also to act as a structural support to the glued slot in the fuselage.

It may also be noted that all holes in all of the fiberglass parts were opened with a dull ax, thrown from across the room, by a person wearing the wrong prescription glasses... or something similar I am sure. They do not resemble in any way the shape the holes were meant to be. In some places, too much material was removed, so some filler will be needed there. In all other places, some care has to be taken to open the holes to something resembling the designed intent. I also opened up the smaller intake on top, as it was originally just a partially scratched in detail.

In these pictures you can see the repair finished. As you can see, now the rear engine intake fits the fuselage reasonably well. Note the piece of ply used to fill the gap as well as act as a support for the patched fuselage.

Images

I don't have satisfactory images of the twist in the fuselage. It was twisted 2.5 degrees from fore to aft. This would have caused many issues with keeping the tail and main wing, not to mention the gear, aligned with each other. I had my two sons help me solve this issue. I had one on either end of the fuselage, each twisting in opposite directions. I then used a heat gun to soften the laminate, to allow it to hold the opposing twist applied. The fuselage was held in place until cool. The fuselage is now reasonably straight. About as straight as I am going to get it using this method.

I tossed the front gear and wheels aside, as they will not be used. They are not anywhere near scale. My goal is to use scale diameter wheels and scale retracts. This means machining them from aluminum and steel stock. This will come later. The gear included with the kit is probably fine for an average build, but this build was not planned to be stock.

A more scale representation of the wheels is 40mm for the front wheel and 45mm for the two rear wheels. I have not yet found any 'rubber' wheels that are suitable. I just may have to make my own. I am not fond of the 'cartoonish' balloon wheels commonly used on models. All the aircraft I have worked on, don't use such wheels. The real Reaper does not use such wheels. In fact, I don't know of any aircraft that do. This makes me wonder why manufacturers make them this way. However, companies that 'do' make scale wheels, only do so in much larger sizes. So this calls for custom made wheels. Again, this is something down the road. Just a pointer to indicate the direction this model will be taking.

Some people want to use retracts in this model. It can be done, but not with stock retract mechanisms. They are typically used with wire type struts. Such struts will not be used in this model. The front strut rotates 129 degrees. The rear struts are close to 100 degrees. All three retract mechanisms will be machined from 6061-T6 aluminum and will operate as scale as possible.

I have to say, the wings, both main and tail are done well. I can't see the inside, but they are formed well, covered reasonably well (minor bubbles and wrinkles), they are straight and from what I can tell, use plywood ribs at least near the root. I do not see any twist in any of the wings. I will however actuate the control surfaces in a scale manner, which will mean making appropriate servo covers. I will not use the CA hinges included in the kit. Rather I will use POR hinges. They apply less load to the servo and allow a pivot point for the control surfaces, as opposed to CA hinges which only provide a flex point for control surfaces and cause unnecessary load on the servo.

Due to the lip on all fiberglass parts, altering the parts to fit well will mean removing the lip. I will have to reshape the lip area and build them up in various places. This is the stage I am presently at. I will add pictures at it progresses. Also, the magnet mounts are not aligned with each other from top to bottom. To add to the problem, the mounts are not parallel with each other. This creates a large gap between magnets, causing a very weak attraction. I do not believe I will use magnets on this build.

TripleW: No, I don't have in person experience with modern drones. Would be nice though. I get any information from research and observing any pictures I can find. I do have A&P experience as well as a healthy engineering history.

Here are some pictures of resetting the position of the hood on the fuselage. The hood in its original state was sitting awkwardly. Tilted a bit to the left and with some very large gaps around the seam.

Some balsa sheet was used to create a filler for the gap. The lip was cut away to create the same sized gap as was evident on both sides. This allows the balsa fill to be of the same thickness all around. The filler sheet was then cut away on the inside, creating a new lip. Next is to mask the fuselage lip to allow for an epoxy/micro balloon fill. The hood will be put in place, aligned, then the epoxy/balloon mixture will be pressed into the remaining seam imperfections. This will create a perfect match between the hood and the fuselage. The masked fuselage lip will prevent the epoxy from sticking to the fuselage, yet the epoxy will bond to the hood lip. From there, general sanding will flush everything up.